Cornering the axionlike particle explanation of quasar polarizations

In a series of papers, it has been shown that the distribution of polarization position angles for visible light from quasars is not random in extremely large regions of the sky. As explained in a recent article, the measurement of vanishing circular polarization for such quasars is an important problem for a mechanism involving the mixing with axionlike particles in external magnetic fields. In this paper, we stress that a recent report of similar coherent orientations of polarization in radio waves further disfavors the need for such particles, as an effect at these wavelengths would be extremely suppressed or would directly contradict data.